1. Field of the Invention
The present invention relates to an inkjet printer for ejecting ink onto a printing medium to thereby form an image.
2. Description of the Related Art
According to a related art, in an inkjet printer of an inkjet type for ejecting very small ink droplets from ejection holes of an inkjet head onto a recording medium so as to form a desired image, a satisfactory image can be obtained when ink ejection from the vary small ejection holes is kept good. It is therefore necessary to prevent thickened ink droplets or foreign matters from adhering to the ejection holes. To this end, in the related art, an operation of so-called flushing is performed independently of an operation of image formation. That is, ink is ejected from the ejection holes so as to remove thickened ink droplets or foreign matters.
In a serial type inkjet printer, the flushing operation can be performed in a region other than a printing medium conveyance portion because an inkjet head is movable in the width direction of a printing medium. However, in a fixed line head type inkjet printer using a conveyance belt for conveying a printing medium, ink is ejected onto the conveyance belt at the time of flushing because a recording head is fixed with respect to a printing medium conveyance portion. Accordingly, in the fixed line head type inkjet printer in the related art, an ink reception region such as a groove or an opening portion is provided in the conveyance belt. Ink is ejected only to the ink reception region at the time of flushing. Thus, the ink is prevented from adhering to the conveyance surface carrying the printing medium thereon (for example, see JP-A-2001-2873771 (pages 4 to 5; and FIG. 3)).
Inkjet printers generally use cut paper as printing media. In recent years, inkjet printers are used for various expanded applications. There is an increasing demand for recording not only on the cut paper but also on a long printing medium rolled up, such as roll paper.
In a typical inkjet printer using roll paper, the roll paper is set upstream in the printing medium feed direction, while the front end of the roll paper is set at the entrance of the conveyance path. Image recording is performed with the roll paper being carried and conveyed on a conveyance belt by a pinch roller (e.g. JP-A-Hei. 10-139239 (pages 4 to 5; and FIG. 1)).